This invention relates to an optical disk fabricating method, optical disk, and optical disk apparatus, and more particularly, to the fabrication, recording and reproduction of optical disks that have been formed according to the so-called land/groove technique.
Currently, the DVD (Digital Versatile Disc) is being proposed as an optical disk apparatus for recording information at high density. The DVD is designed to be able to record 2.6 GB of data on a single side, the recording being performed by irradiating a laser beam having a wavelength of 650 nm onto an optical disk through an optical system having a numerical aperture of 0.6. Using this technique, about one hour's worth of image signals can be recorded on a single side of a disk.
However, a typical home video tape recorder (VTR) has a basic recording time of two hours. Thus, in order for DVD's to become a viable substitute for VTRs, they must be provided with the capability to store more data. For example, although editing or the like can be performed by effectively using the characteristic functions of optical disk such as random access, about three hours' worth of image signal must be recorded in order to make DVDs desirable. In the case of a DVD system, a three hour recording time means that the disk should be capable of storing about 8 GB of data.
For this reason, it is necessary to make effective use of the information recording surface of an optical disk.